Frame Relay IP RTP Priority
This feature module describes the Frame Relay IP RTP Priority feature. It includes the following sections:
•Supported Standards and MIBs and RFCs
•Monitoring and Maintaining Frame Relay IP RTP Priority
The Frame Relay IP RTP Priority feature provides a strict priority queueing scheme on a Frame Relay permanent virtual circuit (PVC) for delay-sensitive data such as voice. Voice traffic can be identified by its Real-Time Transport Protocol (RTP) port numbers and classified into a priority queue configured by the frame-relay ip rtp priority command. The result of using this feature is that voice is serviced as strict priority in preference to other nonvoice traffic.
This feature extends the functionality offered by the ip rtp priority command by supporting Frame Relay PVCs. This feature allows you to specify a range of User Datagram Protocol (UDP) ports whose voice traffic is guaranteed strict priority service over any other queues or classes using the same output interface. Strict priority means that if packets exist in the priority queue, they are dequeued and sent first—that is, before packets in other queues are dequeued.
The strict priority queueing scheme allows delay-sensitive data such as voice to be dequeued and sent first—that is, before packets in other queues are dequeued. Delay-sensitive data is given preferential treatment over other traffic. This process is performed on a per-PVC basis, rather than at the interface level.
Related Features and Technologies
The Frame Relay IP RTP Priority feature is related to the following features:
•IP RTP Priority
•Class-based weighted fair queueing (CBWFQ)
•Weighted fair queueing (WFQ)
•Quality of Service Solutions Configuration Guide, Cisco IOS Release 12.0
•Quality of Service Solutions Command Reference, Cisco IOS Release 12.0
•Class-Based Weighted Fair Queueing
•IP RTP Priority
•Cisco 1600 series
•Cisco 2500 series
•Cisco 2600 series
•Cisco 3600 series
•Cisco 3800 series
•Cisco 4000 series (Cisco 4000, 4000-M, 4500, 4500-M, 4700, 4700-M)
•Cisco 5200 series
•Cisco 7000 series
•Cisco 7200 series
•Cisco 7500 series
This feature runs on the platforms listed. However, it is most useful on voice supported platforms, such as the Cisco 2600 series, Cisco 3600 series, Cisco 7200 series, and Cisco 7500 Route Switch Processor (RSP) series.
Supported Standards and MIBs and RFCs
No new or modified MIBs are supported by this feature.
Frame Relay traffic shaping (FRTS) and Frame Relay Fragmentation (FRF.12) must be configured before the Frame Relay IP RTP Priority feature is used.
•Configuring Frame Relay IP RTP Priority (Required)
•Verifying Frame Relay IP RTP Priority (Optional)
Configuring Frame Relay IP RTP Priority
To reserve a strict priority queue on a Frame Relay PVC for a set of RTP packet flows belonging to a range of UDP destination ports, use the following command in map-class configuration mode.
Note Because the frame-relay ip rtp priority command gives absolute priority over other traffic, it should be used with care. In the event of congestion, if the traffic exceeds the configured bandwidth, then all the excess traffic is dropped.
Router(config-map-class)# frame-relay ip rtp priority starting-rtp-port-number port-number-range bandwidth
Reserves a strict priority queue for a set of RTP packet flows belonging to a range of UDP destination ports.
Verifying Frame Relay IP RTP Priority
To verify the Frame Relay IP RTP Priority feature, use one of the following commands in EXEC mode:
Router# show frame relay pvc
Displays statistics about PVCs for Frame Relay interfaces.
Router# show queue interface-type interface-number
Displays fair queueing configuration and statistics for a particular interface.
Router# show traffic-shape queue
Displays information about the elements queued at a particular time at the VC data link connection identifier (DLCI) level.
Monitoring and Maintaining Frame Relay IP RTP Priority
To tune your RTP bandwidth or decrease RTP traffic if the priority queue is experiencing drops, use the following command in EXEC mode:
Router# debug priority
Displays priority queueing output if packets are dropped from the priority queue.
•Frame Relay IP RTP Priority Configuration Example
Frame Relay IP RTP Priority Configuration Example
The following example first configures the Frame Relay map class called voip and then applies the map class to PVC 100 to provide strict priority service to matching RTP packets:
map-class frame-relay voip
frame-relay mincir 256000
no frame-relay adaptive-shaping
frame-relay ip rtp priority 16384 16380 210
ip address 10.10.10.10 255.0.0.0
frame-relay interface-dlci 100
frame-relay ip rtp header-compression
frame-relay intf-type dce
In this example, RTP packets on PVC 100 with UDP ports in the range 16384 to 32764 will be matched and given strict priority service.
Any Internet Protocol (IP) addresses used in this document are not intended to be actual addresses. Any examples, command display output, and figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses in illustrative content is unintentional and coincidental.
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